It has become nearly impossible to tell Liam Neeson’s action movies apart but, even at age 69, he keeps churning them out.

His latest is “Memory,” which is ostensibly about a hitman who’s beginning to suffer from dementia. For some reason, though, that whole memory loss plotline is subsumed by yet another run-of-the-mill revenge story, this time because Neeson has been ordered to kill a little girl, and that’s over the line for him. But the bad guys he works for don’t take no for an answer, so he becomes a marked man. And according to Movie Law #1,452, he must kill everyone in the chain of command that hired him for the hit.

“Memory” is full of ironies, not the least of which is that its screenwriter forgot about the memory angle — but that’s not all. The actor cast as the FBI agent hot on Liam’s trail is Guy Pearce, who starred in Christopher Nolan’s brilliant “Memento,” in which the hero can’t remember anything from day to day. In that movie, Pearce tattoos clues about his fractured life all over his body so he can see them in the mirror every morning to help reset his brain. In “Memory,” Neeson simply writes stuff on his arm.

Another irony is that “Memory” gets so dense and villain-heavy that I actually forgot who is who, thanks to a cast full of nobodies playing characters spouting predictable, lousy dialogue. Meanwhile, Neeson looks exhausted in every scene, perhaps because he’s doing the same thing he’s done on screen umpteen times before.

I kinda liked “The Ice Road,” a Neeson movie that came out on Netflix last summer (my review is here), but I can’t recommend “Memory,” which I’m giving a 3 out of 10. The final irony is that it will be quickly forgotten.

Opens today in theaters.